Possible cascading ruptures on the eastern section of the Altyn Tagh fault

Understanding how connected fault segments may rupture sequentially or simultaneously to produce large earthquakes is a fundamental problem in earthquake physics and seismic hazard assessment. Addressing this issue requires integrated constraints on fault geometry, slip behavior, and rupture history across interconnected fault systems. The Subei triple junction along the eastern section of the Altyn Tagh fault, which connects thrust (Danghe Nan Shan thrust) and strike-slip fault segments (Altyn Tagh and Yema-Daxue Shan faults), is an ideal site for investigating such cascading rupture processes. In this study, we excavated three new paleoseismic trenches around the Subei junction, including two across the Danghe Nan Shan thrust and one across the Altyn Tagh fault. Detailed stratigraphic logging, identification of abundant paleoseismic indicators, and dense optical stimulated luminescence (OSL) dating constrain the timing of late Quaternary surface-rupturing earthquakes. Our results indicate that three to four surface-rupturing events occurred at these sites during the Holocene, with overlapping age ranges among the different fault segments. By integrating our new paleoseismic constraints with previously studies, we identify at least one Holocene earthquake that likely involved synchronous rupture of the Altyn Tagh fault, the Yema–Daxue Shan fault, and the Danghe Nan Shan thrust. Multicycle dynamic rupture modeling incorporating fault geometry and long-term slip rates further support such cascading ruptures across the strike-slip and thrust fault network. These results provide rare field-based evidence that large earthquakes on the eastern section of Altyn Tagh fault may involve multiple fault segment ruptures. Our findings highlight the importance of considering fault interactions and cascading rupture scenarios when assessing seismic hazard in complex continental fault systems.